Flat-panel display devices such as liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays in the field of display technology have occupied a special place in the field of flat-panel display due to the advantages of light weight, small thickness, low power consumption, high brightness, high definition and so on. In particular, large-size, high-resolution and high-definition flat-panel display devices such as LCD TVs have been dominant in the current flat-panel display market.
Currently, image signal delay is a key factor restricting a large-size, high-resolution and high-definition flat-panel display device. More specifically, image signal delay is mainly determined by the signal resistance R of gate electrodes, gate lines or data lines and relevant capacitance C on a substrate. With the constantly increased size of the display device and the constantly increased resolution, the signal frequency applied by a drive circuit is constantly increased as well; and image signal delay becomes more seriously. In an image display period, a gate line is turned on and pixels are charged; but due to image signal delay, some pixels are not sufficiently charged, resulting in the non-uniform brightness in the displayed images and hence seriously affecting the display quality of the images. In addition, when the resistance of gate electrodes, gate lines or data lines is reduced, image signal delay is reduced, and hence the image quality can be improved.
At present, the method for reducing the resistance of gate lines and data lines mainly is to adopt a low-resistance metal copper (Cu) to manufacture gate lines and data lines. However, the method has the following disadvantages:
As copper (Cu) ions can be easily diffused, and particularly diffused to a gate electrode protective layer, a semiconductor layer or a passivation layer at a high temperature, the performances of a thin film transistor (TFT) can be seriously affected. In particular, in the subsequent high-temperature heating processes on the TFT, due to the increased activity, the copper (Cu) ions can penetrate through an insulating barrier layer and into the semiconductor layer, and hence the performances of the TFT can be seriously affected, and consequently the image quality may become poorer, and even the normal operation of the TFT can be destroyed.
TFTs on a traditional substrate and the manufacturing method thereof have the problems of reduced TFT performances and poorer image quality.